I am looking around for someone with a spare magazine for a Mossberg 144 LSB in .22 cal LR.

... Go to www.GunBroker.com. Scroll down the left side of the page until you come to "Firearms Parts". Then click on "Magazines and Clips". When that page comes up, enter your item you are looking for in the search bar and hit "Search". You may find it easier to work if you just type "Mossberg" in the search bar.